The principal objectives of the proposed investigation are (A) to study the interaction of carcinogenic polycyclic epoxides with bio- molecules which can be related to the chemical carcinogenesis of these epoxides and (B) to develop an effective synthesis of optically active arene oxides and dihydrodiol epoxides and to elucidate their absolute configurations. In vitro, the reaction of carcinogenic and non- carcinogenic polycyclic epoxides with nucleic acid bases will be investigated with a view towards isolation and characterization of the irreversible products of these reactions. The bases will include mononucleotides, oligonucleotides and polynucleotides (e.g., poly (G)). The correlation of the reactivity of the polycyclic epoxides towards bases with their carcinogenic activity will be attempted. The reaction mechanisms of the arene oxides with other bio-molecules such as glutathione will also be investigated in terms of stereochemistry. Optically active arene oxides required for these studies will be made through their resolution at the stage of the cis-alpha-glycol using optically active borates followed by conversion into epoxides. Efforts to elucidate absolute configuration of the arene oxides will utilize exciton chirality cd methods. Effective and stereospecific generation of arene oxides from the appropriate cis-alpha-glycol will be carried out through five-membered derivatives of the latter such as the five-membered siliconium cation. Through these works, pertinent information towards understanding the molecular basis of chemical carcinogenesis might be obtained.